Voltage regulator coarse control device utilizing current limiting reactor means



June 11. 6 c. w. SCHOENDUBE ETAL 3,388,320

VOLTAGE REGULATOR COARSE CONTROL DEVICE UTILIZING CURRENT LIMITING REACTOR MEANS Filed April 23, 1966 2 Sheets-Sheet 1 FORM/6WD TQH/Z/A/G END H [0H0 7 E0 er JPr/ZJL' 46 W June 11. 1968 c .SCH NDUBE ETA 3,388,320

VOLTAGE REGUL ARSE TROL DEVICE UT ZING CURRENT LIMITING REACTOR MEANS Filed April 23, 1966 2 Sheets-Sheet 2 I 50. 74 1 Cf 2m I I Y 46 80 I fiZWfi/fi/fil 44 [fiOf/? Wfl'oewdzlbe,

United States Patent 3 388 320 vorjraou Risoouiroir coAnsE coNrnoL DEVICE UTILIZING CURRENT LIMITING REACTOR MEANS Charles W. Schoenduhe, Lee, and Roger A. Prior, Pittsfield, Mass, assiguors to General Electric Company, a corporationof New York Filed Apr. 28, 1966, Ser. No. 545,949 2 Claims. (Cl. 323-435) This invention relates to voltage regulators and more particularly to a coarse control device for voltage regulators.

As is well understood by those skilled in the voltage regulator art, voltage regulators are used both to maintain voltages at predetermined levels and also to provide regulated voltages to various types of equipment in which the voltage may be varied over a wide range. In the latter case, such as in process equipment, it is often desirable to be able to apply the voltage in very small regulated increments. At other times it is desirable to rapidly change the applied voltage to higher or lower values. To perform such functions requires voltage regulators which have means for applying varying voltages over large increments, usually, by means of a step regulator winding. Further, such regulators will have a fine Vernier control which will provide a plurality of incremental voltage variations within the range of each step of the step regulator winding. Obviously, the vernier adjustment may be either another stepped winding or it may be an induction regulator. As will be understood, it is desirable to provide a coarse control device to provide for large voltage changes by means of the stepped regulator winding. It is also desirable to provide means for operating the coarse control device over the step regulator winding while the various contacts are at zero load current to prevent arcing of the contacts. As is understood this normally requires that the Vernier voltage control be operated through its steps to provide zero load current on the various contacts of the coarse control device prior to the operation of the coarse control device. Of course, it is always desirable to provide voltage regulators as economically as possible, utilizing simple mechanisms which will require relatively little maintenance.

It is therefore one object of this invention to provide a novel voltage regulator having both coarse and fine voltage control utilizing relatively simple contact and control mechanisms.

A further object of this invention is to provide a novel coarse control device for voltage regulators.

A still further object of this invention is to provide a coarse control device for a voltage regulator having a step regulator winding in which the coarse control device alternates between the various taps of the step regulator winding.

Yet another object of this invention is to provide a coarse control device for a voltage regulator which will provide for a reversal of polarity in the Vernier control winding on changing of taps by the coarse control device.

A still further object of this invention is to provide a novel coarse control device which will permit a more rapid transition and higher operating speeds compared to conventional coarse control devices.

In carrying out this invention in one form a voltage regulator is provided having a winding with a plurality of tap sections for varying the voltage provided by the voltage regulators. Tap contacts are provided for the various tap sections. A coarse control device in the form of a tap changer having a pair of rotatable contact fingers is provided and connected in the voltage regulator such that each contact finger will only make electrical contact with alternate ones of the tap contacts. The coarse tap 3,388,320 Patented June 11, 1968 changer is connected to a given load to be regulated through the winding of a vernier voltage regulator.

The invention which is sought to be protected will be clearly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which its various objects and advantages are obtained, as well as other objects and advantages thereof, will be better understood from the following detailed description of a preferred embodiment especially when considered in the light of the accompanying drawing, in which:

FIGURE 1 is a schematic circuit diagram of a voltage regulator showing a preferred form of coarse control device according to this invention in conjunction with a Vernier voltage control in the form of an induction regulator; and

FIGURE 2 is a schematic circuit diagram of an alternate form of Vernier voltage control which may be used with the coarse control device of this invention.

The voltage regulator of this invention provides an improved form of coarse control device. The improved coarse control device will find application in many types of voltage regulators. It is particularly suited for use in the voltage regulator disclosed in application Ser. No. 500,854 filed Oct. 22, 1965, for Voltage Regulators Having Vernier Voltage Control, in the names of I. W. Simpson and R. H. Brennan and which is assigned to the same assignee as this invention.

The description of this invention will now proceed with particular reference to the drawing, wherein like nuerals are used to indicate like parts throughout the various figures. Considering first FIGURE 1, a. preferred embodiment of the coarse control device of this invention is shown in conjunction with a transformer 10 having a tapped or stepped winding 12. The winding 12 is shown as divided into eight equal tap sections by the tap contacts labeled 14, 16, 18, 20, 22, 24, 26 and 28. Each tap contact 14 through 28 is connected to alternate ones of the circularly arranged stationary contact members also labeled 14 through 28. As can be seen from FIGURE 1, a pair of circularly arranged switching devices or contact devices 39 and 32 are provided. Contact device 30 has a contact finger 31 movable between the four stationary contact members 14, 18, 22 and 26. The circular contact device 32 is provided with a movable contact finger 33 which is movable between stationary contacts 16, 2t), 24 and 28. Of course, it will be understood that each of the stationary contact members is connected to the numbered tap contacts and, as can be seen, the contact sections are alternated between the contact device 30 and contact device 32. It will be understood that the showing of the eight contact sections is for purposes of illustration only, since it will be understood that winding 12 may be divided into as many sections as is desired.

The switching devices 30 and 32 are shown as being mounted side-by-side on a panel and a dotted line connection is provided indicating that the contact fingers 31 and 33 are operated in unison. It will be understood that switching devices 30 and 32 may be mounted one above the other on a common shaft to provide the desired unitary operation between the contact fingers 31 and 33. From the above it will be apparent that contact finger 31 of switch 30 operates over contact members 14, 18, 22 and 26, while contact finger 33 of switching device 32 operates over contacts 16, 20, 24 and 28. It will also be understood that the width of the contacts, the spacing between the contacts and the motion of the fingers will be such that one moving finger willtraverse the width of one contact member, making continuous electrical contact therewith, While the other movable finger will move from the forward end of one contact member to the trailing end of the following contact member for each index interval of rotation. Thus as can be seen from FIGURE 1, as contact finger 33 moves over contact member 16, in a clockwise direction making continuous electrical contact therewith, contact finger 31 will simultaneously move from the forward end of contact member 14 to the trailing end of contact member 18. Thus, the next position of contact fingers 31 and 33 will be with contact finger 31 on the trailing end of contact member 18, and contact finger 33 on the forward end of contact member 16. This action produces a hopping over action of one finger over the other as they traverse along the taps of winding 12.

An induction regulator 34 is provided for fine voltage changes. One winding 36 of induction regulator 34 is connected across the fingers 31 and 33, as shown. This winding 36 may be considered a primary winding of induction regulator 34. The other winding 38, considered as the secondary, has one end connected to mid tap 49 on current limiting reactor 42. The other end of winding 38 is connected to any desired load, indicated at 44, in the usual manner. The other side of load 44 is connected to one end of winding 12, as is indicated by lead 46. As will be apparent from FIGURE 1, the current limiting reactor 42 is connected across the fingers 31 and 33 and is provided in the usual manner with the center tap 40.

The operation of the voltage regulator disclosed in FIGURE 1 will now be described. With the contact fingers 31 and 33 bridging contacts 14 and 16, as shown, the mid tap 40 of the current limiting reactor 42 will be at a potential halfway between that of the contacts 14- and 16. The primary winding 36 of the induction regulator 34 is also connected across the contact fingers 31 and 33 and therefore will have a potential equivalent to the tap section between contacts 14 and 16. The potential at the mid tap it) of current limiting reactor .2 will appear across the load 44 through winding 38 of the induction regulator 34. As will be apparent, the winding 38 may be rotated relative to winding 36 to provide a bucking or a boosting voltage to the voltage appearing at the mid tap 40. In the preferred embodiment of this invention the ratio of winding 38 to 36 is A Thus by properly positioning winding 38 the voltage applied to load 44 may be that of either contact 14 or contact 16 or any potential between these values. As will be understood, when winding 38 is in a neutral position with respect to winding 36 no voltage will be induced in winding 38 and therefore the potential applied to load 44 will be that of mid tap 4d of current limiting reactor 42.

Assuming, in the position shown in FIG. 1, that winding 38 is in position with respect to winding 36 to buck the voltage at mid tap 41) to thereby provide a potential at load 44 equivalent to that of contact 14, then as the winding 33 is rotated the potential applied to load 44 will vary until such potential finally reaches the potential of contact 16. The winding 38 will then have been rotated 180. With the potential on load 44 that of contact 16 the contact fingers 31 and 33 may be rotated in a clockwise direction as seen in FIG. 1, with contact finger 31 leaving contact 14, while contact finger 33 slides across contact 16. Since the potential of load 44 is that of contact 16, substantailly all of the load current is in contact finger 33. Therefore, contact finger 31 can be moved from contact 14 with only the circulating currents being broken since there will be no load current flowing in the contact finger 31. As contact finger 31 is rotated to contact 18, contact finger 33 will move across contact 16 until it is at the forward end of such contact. In this position with contact finger 31 on contact 18 and contact 33 on contact 16, the potential applied to load 44 will still be that of contact 16. However, due to the change of contact finger 31 to contact 18 the polarity of winding 36 will reverse and therefore the voltage induced in winding 38 will be a bucking voltage when applied to the potential of mid tap 40 of current limiting reactor 42. Thus, as can be seen, the contact fingers 31 and 33 in shifting from contact to contact will provide a reversal of the polarity of the primary winding 36 of the induction regulator 34. Due to the positioning of the winding 38 of the induction regulator 34 this will still maintain a constant potential on the load 44 in the manner described. As will be apparent, by the use of the coarse control device disclosed in FIG. 1 it is possible to continuously rotate the winding 33 of induction regulator 34 in the same direction, as the contact fingers 31 and 33 are moved from contact to contact in the manner described and maintain a continuous potential on load 44 which may be varied in a continuous manner between the diiierent tap sections of winding 12 without any requirement for reversing winding 33 between changes of contacts. Of course, it will be apparent that after the contact fingers have changed from 14 and 16, as shown, to contacts 16 and 18, the Winding 38 may again be rotated through to raise the potential on load 44 from that of contact 16 to that'of contact 18. Obviously this sequence may be continued for all of the taps on the winding 12.

Of course, it will be understood that the contact fingers 31 and 33 are rotated in unison so as to provide continuous connection between one contact, such as contact 16, while the other contact finger is moving between contacts, such as between contact 14 and contact 18. Obviously, this continuous rotation may be provided by means of a mechanical coupling between fingers 31 and 33 as indicated by the dotted lines in FIG. 1, or as previously mentioned, the contact fingers 31 and 33 may be mounted on a common shaft with the proper space displacement for rotation therewith. Obviously, any method of connection may be provided to obtain rotation in unison between the contacts 31 and 33.

Referring now to FIGURE 2 of the drawing another form of vernier control is shown which may be used with the voltage regulator of this invention. As is shown in FIG. 2, a tapped transformer winding is used as a vernier control in place of the induction regulator of FIG. 1. FIG- URE 2 merely shows the cur-rent limiting reactor 42 with its mid tap 46 in the same manner as shown in FIG. 1, and the arrowed lines labeled to 30 and to 32 will, of course, go to the switching mechanisms 30 and 32 of the voltage regulator shown in FIG. 1 of the drawing. As shown in FIG. 2, a transformer 50 is provided for vernier control having a winding 52 connected across the contact fingers 31 and 33. The other winding 56 is tapped as indicated by the circularly arranged contacts 58, 60, 62, 64, 66, 68, 70, 72 and 74. Switching means are provided having fingers 76, 78 for electrically connecting the various contacts to a current limiting reactor 81) which is center tapped at 82. A load 44 is connected between center tap 82 and one end of winding 12 by means of lead 46. In this embodiment the winding 52 will be provided with 8 N turns while the winding 56 has 8 N turns divided into eight equal sections. When the fingers 31 and 33 are on contacts 14 and 16, respectively, and the fingers 76 and 78 are on contact 66 the voltage applied to load 44 is equal to that at the center point of the tap section between contacts 14 and 16. As can be seen from FIG. 2, contact 66 is connected directly to the mid tap 40 of the current limiting reactor 42. Therefore, in the position shown, contact fingers 76 and 78 and the load 44 are essentially connected directly to the center tap 40 of the current limiting reactor 42. As the fingers '76 and 78 move up from contact 66 toward contact 58 the voltage for each full step will increase by Ms of the tap section voltage. As will be understood each full step is the movement of both fingers 76 and 78' from one contact to the next, that is, a movement of fingers 76 and 78 from contacts 66 to contact 64. Each bridging position of fingers 76, 78 will equal 5 of the vernier tap section voltage. As the fingers 76, 78 reach contact 58 the voltage will have increased by /2 of the vernier tap section voltage. Since the voltage at contact 66 is equal to the center point of the tap section, the movement to contact 58 will bring the voltage to that of one of the tap contacts, such as tap contact 16. As will be apparent, at

this point contact finger 31 can be moved from contact 14 to contact 18 while finger 33 moves along contact 16. The voltage on the contact 58 will be essentially that of contact 16. When the finger 31 reaches contact 18 the polarity will reverse in winding 52, thus providing for an increase in voltage in the opposite direction on the winding 56. The contact fingers 76 and 78 may now be rotated in the opposite direction from contact 58 through 60, 62, 64 around at contact 74, to thereby increase the voltage from contact 16 to contact 18 on main winding 12. Thus by use of the modification in FIG. 2, a Vernier control may be provided for the coarse control device of this invention to provide a continuous increase in voltage by merely reversing the operation of the contacts 76 and 78 after each change of the tap sections on the main winding 12.

Of course, it will be readily apparent to those skilled in the art that the vernier control device disclosed in FIG. 2 of the drawing, which is substantially the same as that disclosed in the aforementioned copending application Ser. No. 500,854, may be provided with reversing switches in the manner disclosed in the aforementioned co-pending application to reduce the size of the vernier control transformer 50.

From the above it will be clear that by means of this invention there is provided a novel, coarse control device for use in a voltage regulator utilizing very simple mechanisms and which will be relatively easily maintained. Also it will be clear that the coarse control device of this invention conforms to all of the advantages and benefits hereinbefore set forth. As will be apparent to those skilled in this art, various changes may be made in the described preferred embodiment of this invention without departing from the spirit and scope of the invention, particularly as it is set forth in the appended claims.

I What is claimed as new and which it is desired to secure by Letters Patent of the United States is:

1. A voltage regulator having coarse voltage control and Vernier voltage control comprising, in combination:

(A) a first induction means, a winding of said first induction means divided into a plurality of tapped sections,

(1) a pair of contact devices, each of said contact devices comprising a plurality of circularly arranged contacts with the contacts of one contact device being connected to said winding at one of said plurality of tap sections alternately with the contacts of said other contact device,

(2) a pair of switching means, one switching means operable with each of said contact devices,

(a) each said switching means including a movable finger, each said movable finger positioned to engage one plurality of circularly arranged contacts on each of said contact devices,

(b) means for moving said movable fingers in unison such that one of said fingers will be in electrical contact with at least one of said contacts,

(3) a current limiting reactor electrically connected between said movable fingers, (4) a center tap on said current limiting reactor,

(a) a second induction means, one winding of said second induction means electrically connected between said movable fingers in parallel circuit relation with said current limiting reactor,

(1) a second winding of said second induction means, means connecting said second winding to said center tap of said current limiting reactor,

(b) said second winding effective to provide bucking or boosting voltages to vary the voltage between said tap sections of said winding of said first induction means, and

(c) means completing a circuit from said center tap of said current limiting reactor to a load through said second winding.

2. A voltage regulator as claimed in claim 1 in which said switching means are connected such that said movable finger of one said switching means moves along one contact of one of said contact devices while the other said movable finger moves from one contact to another contact of the other said contact device, thereby providing a reversal of polarity of said one winding of said second induction means and permitting continuous operation of said second winding of said second induction means.

References Cited UNITED STATES PATENTS 3,100,865 8/1963 Nielsen 32343.5 3,122,698 2/1964 Ladd 323-435 3,349,320 10/1967 Mathes 323-43.5

LEE T. HIX, Primary Examiner.

WARREN E. RAY, Examiner.

G. GOLDBERG, Assistant Examiner. 

1. A VOLTAGE REGULATOR HAVING COARSE VOLTAGE CONTROL AND VERNIER VOLTAGE CONTROL COMPRISING, IN COMBINATION: (A) A FIRST INDUCTION MEANS, A WINDING OF SAID FIRST INDUCTION MEANS DIVIDED INTO A PLURALITY OF TAPPED SECTIONS, (1) A PAIR OF CONTACT DEVICES, EACH OF SAID CONTACT DEVICES COMPRISING A PLURALITY OF CIRCULARLY ARRANGED CONTACTS WITH THE CONTACTS OF ONE CONTACT DEVICE BEING CONNECTED TO SAID WINDING AT ONE OF SAID PLURALITY OF TAP SECTIONS ALTERNATELY WITH THE CONTACTS OF SAID OTHER CONTACT DEVICE, (2) A PAIR OF SWITCHING MEANS, ONE SWITCHING MEANS OPERABLE WITH EACH OF SAID CONTACT DEVICES, (A) EACH SAID SWITCHING MEANS INCLUDING 2 MOVABLE FINGER, EACH SAID MOVABLE FINGER POSITIONED TO ENGAGE ONE PLURALITY OF CIRCULARLY ARRANGED CONTACTS ON EACH OF SAID CONTACT DEVICES, (B) MEANS FOR MOVING SAID MOVABLE FINGERS IN UNISON SUCH THAT ONE OF SAID FINGERS WILL BE IN ELECTRICAL CONTACT WITHAT LEAST ONE OF SAID CONTACTS, (3) A CURRENT LIMITING REACTOR ELECTRICALLY CONNECTED BETWEEN SAID MOVABLE FINGERS, (4) A CENTER TAP ON SAID CURRENT LIMITING REACTOR, (A) A SECOND INDUCTION MEANS, ONE WINDING OF SAID SECOND INDUCTION MEANS ELECTRICALLY CONNECTED BETWEEN SAID MOVABLE FINGERS IN PARALLEL CIRCUIT RELATION WITH SAID CURRENT LIMITING REACTOR, (1) A SECOND WINDING OF SAID SECOND INDUCTION MEANS, MEANS CONNECTING SAID SECOND WINDING TO SAID CENTER TAP OF SAID CURRENT LIMITING REACTOR, (B) SAID SECOND WINDING EFFECTIVE TO PROVIDE BUCKING OR BOOSTING VOLTAGES TO VARY THE VOLTAGE BETWEEN SAID TAP SECTIONS OF SAID WINDING OF SAID FIRST INDUCTION MEANS, AND (C) MEANS COMPLETING A CIRCUIT FROM SAID CENTER TAP OF SAID CURRENT LIMITING REACTOR TO A LOAD THROUGH SAID SECOND WINDING. 